HL7.FHIR.UV.EXTENSIONS\Additional Resource Reference Target - Definitions

FHIR Extensions Pack, published by HL7 International / FHIR Infrastructure. This guide is not an authorized publication; it is the continuous build for version 5.3.0 built by the FHIR (HL7® FHIR® Standard) CI Build. This version is based on the current content of https://github.com/HL7/fhir-extensions/ and changes regularly. See the Directory of published versions

Extension: AdditionalResourceReferenceTarget - Detailed Descriptions

Page standards status: Trial-use

Maturity Level: 1

Definitions for the additional-resource-reference-target extension.

Key Elements Table
Differential Elements Table
Snapshot Elements Table

Guidance on how to interpret the contents of this table can be foundhere

0. Extension
Definition	Allows the relevant work group to indicate and approve which core and additional-resource reference elements may use this additional resource as a target. Optional Extension Element - found in all resources.
Short	Allowed reference targets for an additional resourceOptional Extensions Element
Comments	This enables use of normal Reference.reference in deployments where both the core and additional resource definitions are in scope. Each declared target should be approved by the work group responsible for the referenced element.
Control	0..*
Is Modifier	false
Invariants	ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count())) ext-1: Must have either extensions or value[x], not both (extension.exists() != value.exists())
2. Extension.extension
Definition	May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and managable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.
Short	Additional content defined by implementations
Comments	There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.
Control	10..*
Type	Extension
Is Modifier	false
Summary	false
Alternate Names	extensions, user content
Invariants	ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count())) ext-1: Must have either extensions or value[x], not both (extension.exists() != value.exists())
Slicing	This element introduces a set of slices on `Extension.extension`. The slices areUnordered and Open, and can be differentiated using the following discriminators: value @ url
4. Extension.extension:target
Slice Name	target
Definition	Declares a core or additional-resource reference element that may use this additional resource as a target, as indicated and approved by the relevant work group.
Short	A reference element that may target this additional resourceAdditional content defined by implementations
Control	10..*
Type	Extension
Is Modifier	false
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count())) ext-1: Must have either extensions or value[x], not both (extension.exists() != value.exists())
6. Extension.extension:target.extension
Definition	An Extension May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and managable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.
Short	ExtensionAdditional content defined by implementations
Comments	There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.
Control	20..2*
Type	Extension
Is Modifier	false
Summary	false
Alternate Names	extensions, user content
Invariants	ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count())) ext-1: Must have either extensions or value[x], not both (extension.exists() != value.exists())
Slicing	This element introduces a set of slices on `Extension.extension.extension`. The slices areUnordered and Open, and can be differentiated using the following discriminators: value @ url
8. Extension.extension:target.extension:profile
Slice Name	profile
Definition	Name of the approved FHIR resource (including additional and historical resource names) that contains the declared reference element.
Short	Name of the approved resource that contains the reference elementAdditional content defined by implementations
Control	10..1*
Type	Extension
Is Modifier	false
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count())) ext-1: Must have either extensions or value[x], not both (extension.exists() != value.exists())
10. Extension.extension:target.extension:profile.extension
Definition	An Extension May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and managable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.
Short	ExtensionAdditional content defined by implementations
Comments	There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.
Control	0..0*
Type	Extension
Is Modifier	false
Summary	false
Alternate Names	extensions, user content
Invariants	ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count())) ext-1: Must have either extensions or value[x], not both (extension.exists() != value.exists())
Slicing	This element introduces a set of slices on `Extension.extension.extension.extension`. The slices areUnordered and Open, and can be differentiated using the following discriminators: value @ url
12. Extension.extension:target.extension:profile.url
Definition	Source of the definition for the extension code - a logical name or a URL.
Short	identifies the meaning of the extension
Comments	The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition SHALL be a URI for the Structure Definition defining the extension.
Control	1..1
Type	uri
Is Modifier	false
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
XML Format	In the XML format, this property is represented as an attribute.
Summary	false
Fixed Value	`profile`
14. Extension.extension:target.extension:profile.value[x]
Definition	Value of extension - must be one of a constrained set of the data types (see Extensibility for a list).
Short	Value of extension
Control	10..1 This element is affected by the following invariants: ext-1
Binding	The codes SHALL be taken from For codes, see extended-resource-types (??) (required to `http://hl7.org/fhir/ValueSet/extended-resource-types`) Current and past FHIR resource types (deleted or renamed), and additional resource types (FHIR v6.0.0-ballot4).
Type	code, date, Meta, Address, Attachment, integer, Count, DataRequirement, Dosage, uuid, Identifier, RatioRange, Coding, SampledData, id, positiveInt, Distance, Availability, integer64, Period, Duration, canonical, Range, RelatedArtifact, base64Binary, UsageContext, Timing, decimal, ExtendedContactDetail, CodeableConcept, ParameterDefinition, dateTime, string, oid, instant, ContactPoint, HumanName, Money, markdown, Ratio, Age, Reference, TriggerDefinition, Quantity, uri, url, Annotation, ContactDetail, boolean, Expression, CodeableReference, Signature, unsignedInt, time
[x] Note	SeeChoice of Data Typesfor further information about how to use [x]
Is Modifier	false
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
16. Extension.extension:target.extension:elementId
Slice Name	elementId
Definition	ElementDefinition id or path that identifies the reference element approved to target this additional resource.
Short	ElementDefinition id/path of the reference elementAdditional content defined by implementations
Comments	This value should identify an element of type Reference in the declared resource.
Control	10..1*
Type	Extension
Is Modifier	false
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count())) ext-1: Must have either extensions or value[x], not both (extension.exists() != value.exists())
18. Extension.extension:target.extension:elementId.extension
Definition	An Extension May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and managable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.
Short	ExtensionAdditional content defined by implementations
Comments	There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.
Control	0..0*
Type	Extension
Is Modifier	false
Summary	false
Alternate Names	extensions, user content
Invariants	ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count())) ext-1: Must have either extensions or value[x], not both (extension.exists() != value.exists())
Slicing	This element introduces a set of slices on `Extension.extension.extension.extension`. The slices areUnordered and Open, and can be differentiated using the following discriminators: value @ url
20. Extension.extension:target.extension:elementId.url
Definition	Source of the definition for the extension code - a logical name or a URL.
Short	identifies the meaning of the extension
Comments	The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition SHALL be a URI for the Structure Definition defining the extension.
Control	1..1
Type	uri
Is Modifier	false
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
XML Format	In the XML format, this property is represented as an attribute.
Summary	false
Fixed Value	`elementId`
22. Extension.extension:target.extension:elementId.value[x]
Definition	Value of extension - must be one of a constrained set of the data types (see Extensibility for a list).
Short	Value of extension
Control	10..1 This element is affected by the following invariants: ext-1
Type	string, date, Meta, Address, Attachment, integer, Count, DataRequirement, Dosage, uuid, Identifier, RatioRange, Coding, SampledData, id, positiveInt, Distance, Availability, integer64, Period, Duration, canonical, Range, RelatedArtifact, base64Binary, UsageContext, Timing, decimal, ExtendedContactDetail, CodeableConcept, ParameterDefinition, dateTime, code, oid, instant, ContactPoint, HumanName, Money, markdown, Ratio, Age, Reference, TriggerDefinition, Quantity, uri, url, Annotation, ContactDetail, boolean, Expression, CodeableReference, Signature, unsignedInt, time
[x] Note	SeeChoice of Data Typesfor further information about how to use [x]
Is Modifier	false
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
24. Extension.extension:target.url
Definition	Source of the definition for the extension code - a logical name or a URL.
Short	identifies the meaning of the extension
Comments	The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition SHALL be a URI for the Structure Definition defining the extension.
Control	1..1
Type	uri
Is Modifier	false
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
XML Format	In the XML format, this property is represented as an attribute.
Summary	false
Fixed Value	`target`
26. Extension.extension:target.value[x]
Definition	Value of extension - must be one of a constrained set of the data types (see Extensibility for a list).
Short	Value of extension
Control	0..01 This element is affected by the following invariants: ext-1
Type	Choice of: base64Binary, boolean, canonical, code, date, dateTime, decimal, id, instant, integer, integer64, markdown, oid, positiveInt, string, time, unsignedInt, uri, url, uuid, Address, Age, Annotation, Attachment, CodeableConcept, CodeableReference, Coding, ContactPoint, Count, Distance, Duration, HumanName, Identifier, Money, Period, Quantity, Range, Ratio, RatioRange, Reference, SampledData, Signature, Timing, ContactDetail, DataRequirement, Expression, ParameterDefinition, RelatedArtifact, TriggerDefinition, UsageContext, Availability, ExtendedContactDetail, Dosage, Meta
Is Modifier	false
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
28. Extension.url
Definition	Source of the definition for the extension code - a logical name or a URL.
Short	identifies the meaning of the extension
Comments	The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition SHALL be a URI for the Structure Definition defining the extension.
Control	1..1
Type	uri
Is Modifier	false
XML Format	In the XML format, this property is represented as an attribute.
Summary	false
Fixed Value	`http://hl7.org/fhir/StructureDefinition/additional-resource-reference-target`
30. Extension.value[x]
Definition	Value of extension - must be one of a constrained set of the data types (see Extensibility for a list).
Short	Value of extension
Control	0..01 This element is affected by the following invariants: ext-1
Type	Choice of: base64Binary, boolean, canonical, code, date, dateTime, decimal, id, instant, integer, integer64, markdown, oid, positiveInt, string, time, unsignedInt, uri, url, uuid, Address, Age, Annotation, Attachment, CodeableConcept, CodeableReference, Coding, ContactPoint, Count, Distance, Duration, HumanName, Identifier, Money, Period, Quantity, Range, Ratio, RatioRange, Reference, SampledData, Signature, Timing, ContactDetail, DataRequirement, Expression, ParameterDefinition, RelatedArtifact, TriggerDefinition, UsageContext, Availability, ExtendedContactDetail, Dosage, Meta
Is Modifier	false
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))

Guidance on how to interpret the contents of this table can be foundhere

0. Extension
Definition	Allows the relevant work group to indicate and approve which core and additional-resource reference elements may use this additional resource as a target.
Short	Allowed reference targets for an additional resource
Comments	This enables use of normal Reference.reference in deployments where both the core and additional resource definitions are in scope. Each declared target should be approved by the work group responsible for the referenced element.
Control	0..*
2. Extension.extension:target
Slice Name	target
Definition	Declares a core or additional-resource reference element that may use this additional resource as a target, as indicated and approved by the relevant work group.
Short	A reference element that may target this additional resource
Control	1..*
Type	Extension
4. Extension.extension:target.extension
Control	2..2
6. Extension.extension:target.extension:profile
Slice Name	profile
Definition	Name of the approved FHIR resource (including additional and historical resource names) that contains the declared reference element.
Short	Name of the approved resource that contains the reference element
Control	1..1
Type	Extension
8. Extension.extension:target.extension:profile.extension
Control	0..0
10. Extension.extension:target.extension:profile.url
Type	uri
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
Fixed Value	`profile`
12. Extension.extension:target.extension:profile.value[x]
Control	1..?
Binding	The codes SHALL be taken from extended-resource-types (??) (required to `http://hl7.org/fhir/ValueSet/extended-resource-types`) Current and past FHIR resource types (deleted or renamed), and additional resource types (FHIR v6.0.0-ballot4).
Type	code
[x] Note	SeeChoice of Data Typesfor further information about how to use [x]
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
14. Extension.extension:target.extension:elementId
Slice Name	elementId
Definition	ElementDefinition id or path that identifies the reference element approved to target this additional resource.
Short	ElementDefinition id/path of the reference element
Comments	This value should identify an element of type Reference in the declared resource.
Control	1..1
Type	Extension
16. Extension.extension:target.extension:elementId.extension
Control	0..0
18. Extension.extension:target.extension:elementId.url
Type	uri
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
Fixed Value	`elementId`
20. Extension.extension:target.extension:elementId.value[x]
Control	1..?
Type	string
[x] Note	SeeChoice of Data Typesfor further information about how to use [x]
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
22. Extension.extension:target.url
Type	uri
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
Fixed Value	`target`
24. Extension.extension:target.value[x]
Control	0..0
26. Extension.url
Fixed Value	`http://hl7.org/fhir/StructureDefinition/additional-resource-reference-target`
28. Extension.value[x]
Control	0..0

Guidance on how to interpret the contents of this table can be foundhere

0. Extension
Definition	Allows the relevant work group to indicate and approve which core and additional-resource reference elements may use this additional resource as a target.
Short	Allowed reference targets for an additional resource
Comments	This enables use of normal Reference.reference in deployments where both the core and additional resource definitions are in scope. Each declared target should be approved by the work group responsible for the referenced element.
Control	0..*
Is Modifier	false
Invariants	ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`) ext-1: Must have either extensions or value[x], not both (`extension.exists() != value.exists()`)
2. Extension.id
Definition	Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.
Short	Unique id for inter-element referencing
Control	0..1 This element is affected by the following invariants: ele-1
Type	id
Is Modifier	false
XML Format	In the XML format, this property is represented as an attribute.
Summary	false
4. Extension.extension
Definition	May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and managable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.
Short	Additional content defined by implementations
Comments	There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.
Control	1..*
Type	Extension
Is Modifier	false
Summary	false
Alternate Names	extensions, user content
Invariants	ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`) ext-1: Must have either extensions or value[x], not both (`extension.exists() != value.exists()`)
Slicing	This element introduces a set of slices on `Extension.extension`. The slices areUnordered and Open, and can be differentiated using the following discriminators: value @ url
6. Extension.extension:target
Slice Name	target
Definition	Declares a core or additional-resource reference element that may use this additional resource as a target, as indicated and approved by the relevant work group.
Short	A reference element that may target this additional resource
Control	1..*
Type	Extension
Is Modifier	false
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`) ext-1: Must have either extensions or value[x], not both (`extension.exists() != value.exists()`)
8. Extension.extension:target.id
Definition	Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.
Short	Unique id for inter-element referencing
Control	0..1 This element is affected by the following invariants: ele-1
Type	id
Is Modifier	false
XML Format	In the XML format, this property is represented as an attribute.
Summary	false
10. Extension.extension:target.extension
Definition	An Extension
Short	Extension
Control	2..2
Type	Extension
Is Modifier	false
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`) ext-1: Must have either extensions or value[x], not both (`extension.exists() != value.exists()`)
Slicing	This element introduces a set of slices on `Extension.extension.extension`. The slices areUnordered and Open, and can be differentiated using the following discriminators: value @ url
12. Extension.extension:target.extension:profile
Slice Name	profile
Definition	Name of the approved FHIR resource (including additional and historical resource names) that contains the declared reference element.
Short	Name of the approved resource that contains the reference element
Control	1..1
Type	Extension
Is Modifier	false
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`) ext-1: Must have either extensions or value[x], not both (`extension.exists() != value.exists()`)
14. Extension.extension:target.extension:profile.id
Definition	Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.
Short	Unique id for inter-element referencing
Control	0..1 This element is affected by the following invariants: ele-1
Type	id
Is Modifier	false
XML Format	In the XML format, this property is represented as an attribute.
Summary	false
16. Extension.extension:target.extension:profile.extension
Definition	An Extension
Short	Extension
Control	0..0
Type	Extension
Is Modifier	false
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`) ext-1: Must have either extensions or value[x], not both (`extension.exists() != value.exists()`)
Slicing	This element introduces a set of slices on `Extension.extension.extension.extension`. The slices areUnordered and Open, and can be differentiated using the following discriminators: value @ url
18. Extension.extension:target.extension:profile.url
Definition	Source of the definition for the extension code - a logical name or a URL.
Short	identifies the meaning of the extension
Comments	The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition SHALL be a URI for the Structure Definition defining the extension.
Control	1..1
Type	uri
Is Modifier	false
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
XML Format	In the XML format, this property is represented as an attribute.
Summary	false
Fixed Value	`profile`
20. Extension.extension:target.extension:profile.value[x]
Definition	Value of extension - must be one of a constrained set of the data types (see Extensibility for a list).
Short	Value of extension
Control	1..1 This element is affected by the following invariants: ext-1
Binding	The codes SHALL be taken from extended-resource-types (??) (required to `http://hl7.org/fhir/ValueSet/extended-resource-types`) Current and past FHIR resource types (deleted or renamed), and additional resource types (FHIR v6.0.0-ballot4).
Type	code
[x] Note	SeeChoice of Data Typesfor further information about how to use [x]
Is Modifier	false
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`)
22. Extension.extension:target.extension:elementId
Slice Name	elementId
Definition	ElementDefinition id or path that identifies the reference element approved to target this additional resource.
Short	ElementDefinition id/path of the reference element
Comments	This value should identify an element of type Reference in the declared resource.
Control	1..1
Type	Extension
Is Modifier	false
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`) ext-1: Must have either extensions or value[x], not both (`extension.exists() != value.exists()`)
24. Extension.extension:target.extension:elementId.id
Definition	Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.
Short	Unique id for inter-element referencing
Control	0..1 This element is affected by the following invariants: ele-1
Type	id
Is Modifier	false
XML Format	In the XML format, this property is represented as an attribute.
Summary	false
26. Extension.extension:target.extension:elementId.extension
Definition	An Extension
Short	Extension
Control	0..0
Type	Extension
Is Modifier	false
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`) ext-1: Must have either extensions or value[x], not both (`extension.exists() != value.exists()`)
Slicing	This element introduces a set of slices on `Extension.extension.extension.extension`. The slices areUnordered and Open, and can be differentiated using the following discriminators: value @ url
28. Extension.extension:target.extension:elementId.url
Definition	Source of the definition for the extension code - a logical name or a URL.
Short	identifies the meaning of the extension
Comments	The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition SHALL be a URI for the Structure Definition defining the extension.
Control	1..1
Type	uri
Is Modifier	false
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
XML Format	In the XML format, this property is represented as an attribute.
Summary	false
Fixed Value	`elementId`
30. Extension.extension:target.extension:elementId.value[x]
Definition	Value of extension - must be one of a constrained set of the data types (see Extensibility for a list).
Short	Value of extension
Control	1..1 This element is affected by the following invariants: ext-1
Type	string
[x] Note	SeeChoice of Data Typesfor further information about how to use [x]
Is Modifier	false
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`)
32. Extension.extension:target.url
Definition	Source of the definition for the extension code - a logical name or a URL.
Short	identifies the meaning of the extension
Comments	The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition SHALL be a URI for the Structure Definition defining the extension.
Control	1..1
Type	uri
Is Modifier	false
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
XML Format	In the XML format, this property is represented as an attribute.
Summary	false
Fixed Value	`target`
34. Extension.extension:target.value[x]
Definition	Value of extension - must be one of a constrained set of the data types (see Extensibility for a list).
Short	Value of extension
Control	0..0 This element is affected by the following invariants: ext-1
Type	Choice of: base64Binary, boolean, canonical, code, date, dateTime, decimal, id, instant, integer, integer64, markdown, oid, positiveInt, string, time, unsignedInt, uri, url, uuid, Address, Age, Annotation, Attachment, CodeableConcept, CodeableReference, Coding, ContactPoint, Count, Distance, Duration, HumanName, Identifier, Money, Period, Quantity, Range, Ratio, RatioRange, Reference, SampledData, Signature, Timing, ContactDetail, DataRequirement, Expression, ParameterDefinition, RelatedArtifact, TriggerDefinition, UsageContext, Availability, ExtendedContactDetail, Dosage, Meta
Is Modifier	false
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`)
36. Extension.url
Definition	Source of the definition for the extension code - a logical name or a URL.
Short	identifies the meaning of the extension
Comments	The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition SHALL be a URI for the Structure Definition defining the extension.
Control	1..1
Type	uri
Is Modifier	false
XML Format	In the XML format, this property is represented as an attribute.
Summary	false
Fixed Value	`http://hl7.org/fhir/StructureDefinition/additional-resource-reference-target`
38. Extension.value[x]
Definition	Value of extension - must be one of a constrained set of the data types (see Extensibility for a list).
Short	Value of extension
Control	0..0 This element is affected by the following invariants: ext-1
Type	Choice of: base64Binary, boolean, canonical, code, date, dateTime, decimal, id, instant, integer, integer64, markdown, oid, positiveInt, string, time, unsignedInt, uri, url, uuid, Address, Age, Annotation, Attachment, CodeableConcept, CodeableReference, Coding, ContactPoint, Count, Distance, Duration, HumanName, Identifier, Money, Period, Quantity, Range, Ratio, RatioRange, Reference, SampledData, Signature, Timing, ContactDetail, DataRequirement, Expression, ParameterDefinition, RelatedArtifact, TriggerDefinition, UsageContext, Availability, ExtendedContactDetail, Dosage, Meta
Is Modifier	false
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`)